On Tue, 19 Mar 2024 at 17:05, Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx> wrote: > > On 19/03/2024 17:32, Naushir Patuck wrote: > > On Tue, 19 Mar 2024 at 14:03, Tomi Valkeinen > > <tomi.valkeinen@xxxxxxxxxxxxxxxx> wrote: > >> > >> On 19/03/2024 15:05, Naushir Patuck wrote: > >>> On Tue, 19 Mar 2024 at 13:02, Krzysztof Kozlowski > >>> <krzysztof.kozlowski@xxxxxxxxxx> wrote: > >>>> > >>>> On 19/03/2024 13:57, Naushir Patuck wrote: > >>>>>>>> > >>>>>>>> See writing bindings. Compatibles should be SoC specific. In some cases > >>>>>>>> generic fallbacks make sense, in some note. But don't just choose > >>>>>>>> "generic fallback" because you want. Provide rationale. > >>>>>>> > >>>>>>> If the compatible is SoC specific, I suppose "raspberrypi,rp1-cfe" > >>>>>>> would be the correct string. > >>>>>> > >>>>>> Sure, but then please think what if rp1 is on Rpi6, called exactly the > >>>>>> same (rp1), with some minor differences? Could it be? > >>>>> > >>>>> Yes, this is definitely possible. In such cases, I would expect the > >>>>> hardware to have a version register that would be queried by the > >>>>> driver to adjust for minor differences, and the compatible string > >>>>> remains the same. Does that seem reasonable? > >>>> > >>>> The "would expect" is concerning. The register(s) must be there already, > >>>> with proper value. > >>>> > >>> > >>> A version register already exists in the current hardware, so we will > >>> update it to identify future hardware revisions. > >> > >> But that's a version register for the FE block, not for the whole > >> module, right? Are you suggesting that you'll make sure the FE version > >> will be changed every time anything in the bigger CFE block is changed, > >> and thus the FE version would also reflect the whole CFE version? > > > > Yes, we will update the FE versioning when either CSI2 / FE blocks are updated. > > > >> > >> Can there be versions without the FE block, with just the CSI-2 parts? > > > > There is no version register just in the CSI2 block in isolation, so > > this is not possible. > > I meant could there be a future RPx with only the CSI-2 parts on it, no > FE? In which case we would not have any register for the version. But > then, that would be a rather big change, so a different compatible > string would be in order. > > So, while it's not exactly a perfect version register, I think it will > work fine, assuming the HW people will actually increase the version > also for changes outside FE. > > >> > >> Also, I'm still wondering about the RP1 part there in the compatible > >> string. Is it necessary? The CFE is located in the RP1 co-processor, but > >> is that relevant? > >> > >> Is there a versioning for the whole RP1 chip? Maybe it's going to the > >> wrong direction if we use the board/SoC for this compatible name, as > >> it's actually the RP1 where the CFE is located in, not the SoC. > >> > > > > I don't really know the conversion required to answer this one. > > Logically CFE is on RP1, so it makes sense to me to have "rp1" in the > > string, but I will follow the judgment of the maintainers. > > Well, my thinking here was that if we have a register from which to read > the version, and Raspberry Pi would create a new co-processor, RP2, with > the same CFE. Would we then have "raspberrypi,rp1-cfe" and > "raspberrypi,rp2-cfe", even if there are no changes? Or would a plain > "raspberrypi,cfe" do for both? > > In other words, if we don't need the "rp1" for versioning purposes, > should it then be dropped? I agree with the above, you've convinced me that "raspberrypi,cfe" might be the more appropriate string, or a convincing argument for that to be a fallback string. Naush > > On the other hand, maybe it is safer to just keep the "rp1" there anyway... > > Tomi >
